What a supplement is
A supplement is a request to revise the approved scope of work on an open claim. Your contractor sends the insurer an itemised list of work that the original estimate did not include, with the reason each item is needed and evidence that it is. The insurer reviews it, approves what it accepts, and issues a revised estimate at a higher replacement cost.
It is worth being clear about what it is not. It is not a complaint, an appeal, or an accusation that the adjuster did their job badly. Adjusters write estimates from what can be seen with the old roof still on. Supplements exist precisely because everybody knows that is an incomplete view.
When you will need one
Most commonly at two moments. The first is before work starts, when your contractor prices the job properly and finds the estimate is missing items that were visible all along. The second is mid-tear-off, when the old shingles come up and reveal what nobody could see.
Typical supplement items on a roof claim:
- Decking replacement. Rotten, delaminated or spaced sheathing that only appears once the covering is off. Usually priced per sheet.
- Code-required upgrades. Ice-and-water shield to the current local requirement, drip edge, ventilation, and in some jurisdictions a second layer of underlayment or full re-nailing of the deck. These are triggered by the building code, not by the damage.
- Steep and high charges. Pitches above a certain slope and roofs above a certain height carry additional labour rates that a desk estimate sometimes misses.
- Flashing, pipe boots, and step flashing that cannot be reused.
- Detached structures and accessories — a garage, a shed, gutters, or a satellite mount that was never in the scope.
- Layer removal. A second or third existing layer of shingles doubles or triples the tear-off labour.
- Material availability. Where the specified product is discontinued and the replacement costs more.
Who files it
Your contractor, in almost every case. They have the estimating software, they know the line item codes the insurer’s platform expects, and they are the ones who saw the deck. A supplement written in the same format as the original estimate is reviewed far faster than a letter from a homeowner describing the same thing in prose.
Your job is different and still important: you are the policyholder, so you are the one the insurer has a contract with. You keep the paperwork moving, you keep a record of what was sent and when, and you are the one who can escalate if nothing happens.
What a supplement needs to succeed
- Photographs, taken before the evidence disappears. This is the single biggest cause of denied supplements. Once the bad decking is in a skip, it is very hard to prove it existed. Photograph every sheet replaced, in place, with something in frame for scale, before it comes off.
- An itemised list, not a total. “Additional work: $3,400” is a request the reviewer cannot approve. Each item needs a description, a quantity, a unit and a price.
- A reason per item. Damage, code requirement, or concealed condition. Code items should name the code section or the local requirement.
- The claim number on everything. Files get large. Anything unlabelled gets lost.
- A date-stamped submission. Email, so you have the timestamp without asking anyone.
Where the item is a code upgrade, check your ordinance-and-law coverage before assuming it is payable. Most policies carry it as a percentage of the dwelling limit, and code items come out of that sub-limit rather than out of the main coverage.
What to expect
Supplements are routine, and the usual outcome on well-documented items is approval — often partial. It is normal for a reviewer to accept the decking and the drip edge, question the steep charge, and ask for a photograph of something you have already sent.
Expect it to be slow rather than hostile. Files sit. The most effective thing you can do is follow up on a fixed schedule, in writing, referencing the date of the previous message. A polite, dated paper trail moves a claim faster than any amount of urgency on the phone.
If a re-inspection is requested, that is a normal step. Try to have your contractor present for it — the conversation between two people who both write estimates for a living resolves more in twenty minutes than a month of correspondence.
A worked example
The adjuster’s approved replacement cost is $18,000. Tear-off begins and eleven sheets of decking are found to be rotten. The local code requires ice-and-water shield at the eaves, which the estimate did not include.
The contractor photographs each sheet in place, then files a supplement itemising the eleven sheets at the platform’s unit rate, the ice-and-water shield by the square, and the additional labour. The insurer approves the decking and the shield, and asks for photographs of the third item, which the contractor supplies.
The revised replacement cost is $21,300. Depreciation is recalculated against the new total, and the deductible is unchanged — it was applied once, at the start, and a supplement does not apply it again.
The homeowner receives the difference in two parts, on the same two-payment structure as the original settlement: the actual cash value portion now, the recoverable depreciation once the job is invoiced as complete.
The roof claim calculator shows the gap between the adjuster’s replacement cost and your contractor’s bid, and drafts a covering note for the supplement with your figures in it.
Timing, and the one deadline that matters
File the supplement while the claim is open and while the evidence still exists. Supplements submitted after final payment and file closure are much harder, though a closed file can normally be reopened where there is a genuine reason.
Separately, your policy has a window for completing the work and claiming the recoverable depreciation — commonly 180 days, twelve months or twenty-four months from the date of loss. A supplement under review does not pause that clock by itself. If the review is going to run you close to the deadline, ask for an extension in writing before the deadline passes, not after.
If a supplement is denied
Ask for the denial in writing, with the specific reason for each item. Vague denials are much harder to act on and much easier to overturn once they are written down.
From there the options are, roughly in order of cost: resubmit with better evidence, ask for a re-inspection, escalate to the adjuster’s supervisor, invoke the appraisal clause in your policy if it has one, complain to your state department of insurance, or take advice from a licensed public adjuster or an attorney. The first three are free and resolve most of it.
General guidance on the supplement process used by residential property insurers in the United States. Procedures, line item pricing and code requirements vary by carrier, platform and jurisdiction, and your policy wording governs your claim. Not legal, claims or public adjusting advice.